• Journal of Environmental Science International
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• v.8 no.3
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• pp.371-377
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• 1999

The effects of benzamidoxime concentration, solvents and temperature on the degree of metal extraction were investigated to apply benzamidoxime to heavy metal extraction as chelating agent. Benzamidoxime was synthesized from benzonitrile with hydroxylamine. The chemical structure of benzamidoxime was identified. The degree of heavy metal extraction was increased with increasing the concentration of benzamidoxime and decreasing the extraction temperature. Benzamidoxime was found to be an concentration of benzamidoxime and decreasing the extraction temperature. Benzamidoxime was found to be an effective extractant for Cu-extraction by benzene or chloroform. The relationship between the thermodynamic overall equilibrium constant and absolute temperature was expressed as log K = -5.56 ＋ $855T^{-1}$. Heat of extraction, $$\Delta$H^0$ were calculated from overall equilibrium constants at various temperature and the extraction reactionby benzamidoxime was found to be exthothermic.

• Archives of Metallurgy and Materials
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• v.65 no.4
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• pp.1281-1285
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• 2020

Recently, since the demand of rare earth permanent magnet for high temperature applications such as an electric motor has increased, dysprosium (Dy), a heavy rare earth element, is becoming important due to severe bias in its production. To fulfill the increasing need of Dy, recycling offers as a promising alternative. In recycling of rare earths, Hydro-metallurgical extraction method is mainly used however it has adverse environmental effects. Liquid metal extraction on the other hand, is an eco-friendly and simple method as far as the reduction of rare earth metal oxide is concerned. Therefore, liquid metal extraction was studied in this research as an alternative to the hydro-metallurgical recycling method. Magnesium (Mg) is selected as solvent metal because it doesn't form intermetallic compounds with Fe, B and has a low melting and low boiling point. Extraction behavior of Dy in (Nd,Dy)-Fe-B magnet is observed and effect of Mg ratio on extraction of Dy is confirmed.

• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.171-178
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• 2013

BACKGROUND: Consensus of heavy metal phytoavailability in soils needs to be introduced for soil management protocols in relation to safer food production in the contaminated agricultural soils. For this, setting up the method for evaluation of metal phytoavailability in soil is an essential prerequisite. METHODS AND RESULTS: The current study was carried to select a proper single extraction method for determination of phytoavailable metal concentration in soil. Two extraction methods were examined including 1 M $NH_4NO_3$ extraction and 0.01 M $Ca(NO_3)_2$ extraction methods using 142 soil samples collected from the agricultural soils nearby abandoned mining area in Korea. Corelation analysis was conducted between phytoavailable metal concentrations and soil properties potentially influencing on the metal phytoavailability. Both methods showed similar significance (p<0.001) in correlation with soil properties such as soil pH. However, higher correlation coefficients between phytoavailable metal concentrations and soil properties were observed when used $Ca(NO_3)_2$ extraction rather than using $NH_4NO_3$ extraction. CONCLUSION(S): It appeared that 0.01 M $Ca(NO_3)_2$ extraction was better option for determination of phytoavailable metals in soils and further study to test the efficiency of this method is required in combination with plant uptake.

• Smart Structures and Systems
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• v.29 no.6
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• pp.767-775
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• 2022

Metal additive manufacturing (AM), also known as metal three-dimensional (3D) printing, produces 3D metal products by repeatedly adding and solidifying metal materials layer by layer. During the metal AM process, products experience repeated local melting and cooling using a laser or electron beam, resulting in product defects, such as warpage, cracks, and internal pores. Such defects adversely affect the final product. This paper proposes the in situ monitoring-based warpage prediction of metal AM products with experimental feature extraction. The temperature profile of the metal AM substrate during the process was experimentally collected. Time-domain features were extracted from the temperature profile, and their relationships to the warpage mechanism were investigated. The standard deviation showed a significant linear correlation with warpage. The findings from this study are expected to contribute to optimizing process parameters for metal AM warpage reduction.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.236-246
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• 2006

In this study, we give insight into questionable results that can be encountered in the conventional sequential extraction of heavy metals (Cd, Cu, and Zn) from soils. Objectives of this study were to determine the extraction variability of exchangeable (EXC)-metals as using six different EXC-extractants commonly accepted, and to investigate selectivity problems with carbonates bound (CAB)-metal fraction, a buffered acetate (1.0 M NaOAc; pH 5.0) extractable-metal fraction, leading to erratic results in especially non-calcareous soils. The contents of EXC-metals were markedly varied with the different extractability of various EXC-metal extractants used. The contents of EXC-Cd fraction were ranged from 2.0 to 74.3% of total Cd content in all of the metal spiked soils studied. The contents of EXC-Zn fraction extracted with the different EXC-extractants were varied with soil types, which were from 0.4 to 3.9% of total Zn in the calcareous soils, from 7.6 to 17.9% in the acidic soil, and from 13.6 to 56.8% in the peat soil. However, the contents of EXC-Cu fraction were relatively similar among the applications of different EXC-meal extractants, 0.2 to 2.1 % of total Cu, in all soils tested. Also, these varied amounts of EXC-metal fractions, especially Cd and Zn, seriously impacted the contents of subsequent metal fractions in the procedure. Furthermore, the CAB-Cd, -Cu, and -Zn fractions extracted by the buffered acetate solution were in critical problem. That is, the buffered acetate solution dissolved not only CAB-metals but also metals that bound or occupied to subsequent fractions, especially OXD-metal fraction, in both calcareous and non-calcareous soils. The erratic results of CAB-fraction also seriously impacted the amounts of subsequent metal fractions. Therefore, the conventional sequential extraction should be reconsidered theoretically and experimentally to quantify the target metal fractions or might be progressively discarded.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.663-672
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• 2007

The mutual separation behavior of actinides and rare earths in a countercurrent multistage reductive extraction system was predicted by computer calculation. The distribution information for actinides and rare earths in the reductive extraction systems of LiCl-KCl/Cd and LiCl-KCl/Bi was collected from literature and then it was used for the calculation of a multistage extraction. The results of the concentration profiles throughout the extraction cascade, recovery yields of various metal solutes, and separation factors between the actinides and rare earths were calculated. The effects of the major process parameters, such as reducing agent content in the metal phase, number of stages, and salt/metal flow ratio, etc., on the extraction behavior were also examined.

• Journal of Magnetics
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• v.11 no.2
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• pp.98-102
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• 2006

It was examined in this study that magnetic beads, which are assumed to be environmentally functional, could be effective in processing heavy metals that are water pollutants. For the purpose, magnetic beads containing carboxyl groups, which has strong binding force with heavy metals, are mixed with each Cd, Pb, Ni, Cu and Cr(III) solution, then stirred in pH 6. As a results of the process, it was proven that heavy metals bind quickly with magnetic beads through the reaction. In order to analyze heavy metal concentration, magnetic beads bind with heavy metal were collected by external magnetic force and dissolved in acid. The graphite furnace AAS was used to get heavy metal concentration melted in the acid solution. The results showed that heavy metal extractions by magnetic beads were influenced by the type and the concentration of a heavy metal, and over 90% of a heavy metal can be extracted in ppm level save for Cr(III). It was also examined in the study whether heavy metal extraction is influenced when other ions exist in each heavy metal solution. According to experiment, adding other heavy metals to a solution did have little influence on extracting an intended heavy metal. But in case salt or heavy metal chelate was added, Ni extraction changed sensitively although extracting other heavy metals were influenced only when the concentration of an added substance is high. In conclusion, it was shown that magnetic beads could be used to treat wastewater with relatively high heavy metal concentration.

• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.95-105
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• 2011

Total extraction method and environmental standards for heavy metals in soils were revised in regulation recently. In case of Area 3, as the law amended, the soil pollution level has gone up to 4 to 13 times higher depending on the type of heavy metal. In this study, it compares the properties of heavy metals of soil by sequential extraction and total extraction methods depending on the analysis method, using the soil around mine. In case of arsenic, the soil pollution level has gone up to 4 times higher, but 6 to 10 times in the sample soil. Also, according to the results of portability evaluation depending on the type of existence form of heavy metal it exists as residual form in mine waste rock, which is less likely to move, while it exists as migrated form in tailing. Therefore, it should be considered to evaluate the soil pollution and decide the contaminated bounds depending on the existence form of heavy metals on soil to restore the polluted soil.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.423-427
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• 2005

The bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex-272) and sodium diethyl- dithiocarbamate (NaDDC) ligands were used to extract of metal ions ($Cd^{2+},\;Co^{2+},\;Cu^{2+},\;Pb^{2+},\;Zn^{2+}$) in supercritical $CO_2$. Experiments showed a strong synergistic effect and better extraction efficiency if the two ligands were used together. In-situ UV-visible observation indicates that NaDDC in the water/supercritical $CO_2$ started to decompose slowly. The synergistic effect seems to come from the deprotonation of the organophosphorus ligand by amines from the decomposed NaDDC. The enhancing role of amines was confirmed using the mixture of Cyanex-272 and diethylamine(DEA) in the metal extraction.

• Analytical Science and Technology
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• v.10 no.1
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• pp.60-65
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• 1997

Solvent extraction of alkali metal and alkaline earth metal cations by mono-crown ether(benzo-15-crown-5) and bis-(crown ether)s(ethylenediamine bis(4'-formyl benzo-15-crown-5)) containing benzo-15-crown-5 moieties were investigated with water-chloroform system at $25^{\circ}C$. The order of the extraction equilibrium constants($K_e$) and the complexation constants($K_c$) for the alkali metal and alkaline earth metal cations with mono-crown ether and bis-(crown ether)s were Ca(II)>Na(I)>Sr(II)>K(I)>Mg(II)>Rb(I) and Sr(II)>Ca(II)>K(I)>Rb(I)>Mg(II)>Na(I) respectively. These results were explained in terms of the size effect of metal cation and electron density effect. Also, the bis-(crown ether)s was found to extract metal cations more effectively than the corresponding mono-crown ether.